This goes out to all of the Seville owners. I've been considering a STS for me and my wife, but I have been hearing horror stories about how much of a PITA it is to work on them. The starter is in the middle of the engine, you need a special tool just to replace the water pump, etc. etc. etc. Worst of all, I've heard that when they get hot, they need head gaskets. It sounds like a real nightmare. Any thoughts on this? Thanks.
I have never replaced a starter in a Northstar engine so I can't comment on it. I have replaced a water pump in my 94 Eldorado. It was indeed a pain because it was fused in over the course of 220,000 miles and so I needed to remove it with a 1/2-inch impact wrench 735 Ft. Lbs. reverse torque. Some people use a breaker-bar. But some have little trouble replacing a Northstar water pump. So to answer your question: Yes, you do need a special tool and it can be difficult to replace a Northstar water pump. The tool can be purchased at an autoparts such as Advance Auto for about $25 or can be rented.
Regarding head gasket problems, Northstar engines can blow head gaskets. Some will tell you the head bolts pull which causes head gaskets to blow as a result. However, the primary cause of blown head gaskets is attributable to neglected antifreeze which in turn allows acid to weaken head gaskets. It's very important that you always maintain antifreeze at least as recommended in order to help protect not only the engine in general but the head gaskets as well. My '94 Eldorado has 228,000 miles on it and I have never experienced head gasket problems.
As far as oil burning, Northstar engines, particularly the early years (93-98) were know to burn oil. The Northstar has been redesigned from what I understand to address oil burning. According to a Northstar engineer this was due to the rough honing process used by GM in order to facilitate upper cylinder lubrication. In other words, a slightly roughened surface facilitates oil retention in the upper cylinder and thus better lubrication. As a result, however, the oil left in the upper cylinder is burned, then replaced and so on. I have heard that a burn rate of 1-2 quarts over a thousand miles is acceptable. Interestingly though, I just bought another '94 Eldorado and it appears not to be burning oil at all. I went 3,000 miles between oil changes and didn't need to add any oil. I have read some posts from others stating that they also don't need to add oil. So, it appears that most Northstar engines burn oil (some at higher rates than others) but it's considered acceptable up to a certain point.
Regarding other repairs:
Alternator: Another pain in the butt because it's mounted near the A/C compressor on the passenger side and it must be removed buy dropping it and there's not a lot of room to work with. I've replaced a couple of alternators in a Northstar.
Spark Plugs: Not too difficult. Four plugs are easily accessible at the front of the engine and four near the fire wall. To remove the plugs near the fire wall you will need to remove the Electronic Control Module (at least on the earlier models) and then you will have easy access to the plugs.
Air Filter: Easy. Just loosen top stabilizer bar bolt and remove the lower bolt and swing bar out of way and then you will have easy access to the air box.
Heater Core: Not too difficult. Remove glove box, Power Train Control Module (one bolt), remove heater core cover, disconnect two lines secured by clamps and pull core out from inside the passenger compartment. I must say the heater core is an easy job compared to removing the entire console as is required in a lot of models.
Any particular questions about engine work, please post and I'll try to answer them.
